There's nothing inherently wrong with adapting a book into a movie. Some of the best and most affecting American films have been based on novels -- The Godfather, Psycho, To Kill a Mockingbird, and I'm just randomly culling from AFI's 1998 list -- and it makes sense, in a way. Rather than take a chance on creating a new story, a writer or director or team of producers can start with one they know has had an impact on at least a few people. It's a totally respectable corner to cut, as it were. But the big problem that can come with an adaptations is when the finished film feels like an adaptation, that is, feels like a slipshod assembly of characters and scenes that should probably mean more and that carry an air of importance that's impossible to justify. Right behind that one is when the film deviates from the book's central tone or voice (which is fine and even understandable) but forgets to replace it with one just as engaging or purposeful (which is pretty obviously a bad idea). It's those two main problems that plague the lifeless and illusory Youth in Revolt, which unfolds with all the boredom and let's-get-this-over-with feeling that occurs when a film based on a book clearly doesn't feel like trying to live up to its origins. C.D. Payne's 1993 novel Youth in Revolt isn't a masterpiece, but director Miguel Arteta's film version comes off as almost embarrassed to be seen. It lacks the punch of its forebear's narrative and the courage of the childish convictions that could sell a story like this one. In short, it's a watered-down version of a story that doesn't exist, and leaves an accordingly fleeting impression on the viewer.

The screenplay by Gustin Nash pays lip service to Payne's novel by importing whole swaths of voice-over and character traits that immediately feel as unmoored as you'd expect of people and words yanked from some larger source and not given a new reason to stand on their own. Nick Twisp (Michael Cera) is a horny 16-year-old with an unceasing focus on sex, living in Oakland with his mom (Jean Smart) and her boyfriend (Zach Galifianakis, given precious little screen time). He's got a best friend used in about three scenes, so I won't bother naming him here except to point out that, for being the main character's best friend, he's used hardly at all. This is what I'm talking about when I say the book's trappings have been simply shoved onto the screen with seemingly little thought behind them: Either have Nick's friend play a role in his life in some way, or ax the character. He appears too often to be written off but not often enough to have an impact.

So Nick's unhappy and sexually frustrated -- the film opens with him frantically masturbating to Hustler, though he never does it again -- and forced to take a week-long vacation to a trailer park with his mom and her guy, which is where he meets Sheeni Saunders (Portia Doubleday), an alluring teen who takes advantage of her looks and intelligence to lead Nick along. Their awkward relationship is somewhere between summer fling and hopeless subservience, as Nick follows his hormones' lead and does whatever Sheeni requires, though in some cases (his accidental tumescence when applying her sunscreen) he winds up only further shaming himself. This is the stuff in the film that's the most enjoyable for the way it sees these two characters working through the confusion and headaches of being a teen, especially in the way it captures Nick's helplessness in the gaze of Sheeni, whom he perceives to be wiser simply because she's a little inscrutable.

But for all Nick's journal entries, which provide the voice-over, about being a thwarted virgin who's desperately trying to get laid, Cera's actual performance comes off like a typical Cera performance of late: hyper-intelligent and droll, in direct contrast with his character's supposed sheepishness and inexperience. Part of this is just the unavoidable danger of making a movie about teens. Cera was 20 when the film began rolling, and though he's still slight enough to play a little younger, he doesn't have the energy to play the amped-up horndog Nick is apparently supposed to be. It's as if he's asked to play Jonah Hill's role from Superbad, when he's clearly better suited to the quiet observationalist.

When Nick and his family leave the trailer park, he resolves to do everything he can to get back to Sheeni, and invents an alternate personality named Francois Dillinger to carry out the darker fantasies he'd never do himself. Arteta's come up with a cute way of representing Nick's warring halves by literally externalizing his dark side: Francois often stands next to Nick, egging him on while smoking a cigarette and acting the way a 16-year-old thinks a cool person would act. Some of his words are just for Nick, and some turn out to be the things Nick's saying to other people, even though we see Francois doing the talking. Much of the film is blandly executed, and the occasional animated interstitials meant to indirectly invoke Nick's habit of fanciful invention feel inorganic and cheap, as if no better representation could be found and these seemed arty enough. But the visual of Nick dealing with his own dark side, even comically, is one that could only be done like this in film, and as a result, these are usually the sequences that work the best because Arteta's actually making something new instead of transcribing something old.

Unfortunately, most of the film doesn't follow suit. Nick's desire to see Sheeni again leads to some oddly subdued hijinks -- I say "oddly" because arson, destruction of property, and a shirtless Fred Willard would usually make for a pretty energetic confluence -- that unspool with a speed betraying the literary roots. It's as if, rather than make a story about Nick, Arteta and Nash were determined to condense the book into a detail-oriented but unenjoyable race through the plot highlights most people wouldn't even know they were missing. The supporting cast, including Steve Buscemi as Nick's biological father, isn't terrible, but that's because they're not given much to do aside from hassle Nick. It's Cera's film to carry, and he drags it across the finish line more to get it finished than anything else. The end credits featured another animated sequence supposedly detailing the lives of the characters now that the story proper has ended and moved on, but as it jumped from person to person, there was no feeling of happiness or familiarity, merely the sense that these people were supposed to mean something to someone, maybe me. That's where Youth in Revolt fails: It assumes that you're there out of love for Nick and the inhabitants of the book, and it doesn't bother to earn that love on its own.